Semiempirical investigations on the stabilization energies and ionic hydrogen-bonded structures of F−(H2O)n and Cl−(H2O)n (n = 1–4) clusters
الموضوعات : Journal of Theoretical and Applied Physics
Qi Wang
1
(Department of Chemistry, Tsukuba University)
Kimichi Suzuki
2
(Research Institute for Nanosystem, National Institute of Advanced Industrial Science and Technology)
Umpei Nagashima
3
(Department of Chemistry, Tsukuba University;Research Institute for Nanosystem, National Institute of Advanced Industrial Science and Technology)
Masanori Tachikawa
4
(Quantum Chemistry Division, Graduate School of Science, Yokohama City University)
Shiwei Yan
5
(College of Nuclear Science and Technology, Beijing Normal University)
الکلمات المفتاحية: Semiempirical potential, molecular orbital calculations, Ionic hydrogen, bonded structures, Halide anion water clusters,
ملخص المقالة :
AbstractSeveral semiempirical methods were utilized to analyze the structures and stabilities of X−(H2O)n (X = F, Cl; n = 1–4) clusters with respect to the number of water molecules through their comparison with ab initio molecular orbital calculations. Our results show that the recently developed PM6-DH+ semiempirical method can provide reasonable binding energies of hydrated fluoride and chloride ion clusters, which are consistent with the corresponding experimental results. For the optimized geometries of X = F, however, the semiempirical methods show that the global minima are close to HF(OH)−(H2O)n−1 structures, which are different from the ab initio calculations. Meanwhile, the topological characteristics for the global minima of X = Cl obtained by semiempirical methods have the same symmetries with ab initio calculations. All calculation levels agree on the trend of decreasing ion-water interaction with the increasing number of water molecules. We also found a new structure of Cl−(H2O)4 with a second hydration shell as a complement of previous studies. Those are very important data for our near-future study of on-the-fly semiempirical molecular dynamics (MD) or path integral MD simulation.PACS36.40.Mr, 31.15.bu, 31.15.A-
